Belemnoidea indet
Geological Time: Early Cretaceous, Aptian/Albian Stage
Size: Fossil is 26 mm long by 6 mm across on a 55 mm by 30 mm matrix
Fossil Site: Maree Formation, Coober Pedy, South Australia
Code: TUS20-29
Price: $695.00
 Description:
This specimen comes from Coober Pedy in Australia, a region renowned
for its opal production. Indeed, Coober Pedy is known as the opal
capital of the world. It is the alignment of the hydrated silica spheres
which ultimately results in the rainbow effect of precious opal, the
result of deflection and diffraction of light as it passes through
the planes of hydrated silica molecules. The size of the spheres impacts
the colors seen, with smaller spheres resulting in blues and larger
spheres in reds. The predominant colors here are purple and blue.
The opalized state is typical of what is found, and is a consequence
of the fact that the back part of the shell, known as a guard or rostrum
is the part of the organism subject to preservation, primarily due
to infilling of a cast of the shell by silica. Many types of opalized
fossils have been found, from individual dinosaur bones and belemnites,
to entire opalized Plesiosaur skeletons valued in excess of a million
dollars. |
